High acid ionomers and golf ball cover compositions comprising same

ABSTRACT

The present invention is directed to new metal cation neutralized high acid ionomer resins and to golf ball cover compositions containing these new resins. When the new high acid ionomer resins are utilized to manufacture a golf ball, the golf ball produced thereby exhibits properties of improved distance without sacrificing characteristics such as playability and/or durability when compared to low acid ionomer and/or low acid/high acid ionomer blends.

This is a file wrapper continuation of application Ser. No. 08/366,365,filed Dec. 29, 1994 now abandoned; which is a file wrapper continuationof application Ser. No. 07/901,660 filed Jun. 19, 1992 now abandoned.

FIELD OF THE INVENTION

The present invention relates to new metal cation neutralized high acidionomer resins and to improved golf ball covers made from these resins.The improved golf ball covers are useful for producing golf balls,particularly multi-piece balls, exhibiting enhanced travel distancewhile maintaining the playability and/or durability characteristicsnecessary for repetitive play.

BACKGROUND OF THE INVENTION

Ionomeric resins are polymers containing interchain ionic bonding. As aresult of their toughness, durability, and flight characteristics,various ionomeric resins sold by E. I. DuPont de Nemours & Company underthe trademark “Surlyn®” and more recently, by the Exxon Corporation (seeU.S. Pat. No. 4,911,451) under the trademarks “Escor®” and the tradename“Iotek”, have become the materials of choice for the construction ofgolf ball covers over the traditional “balata” (trans polyisoprene,natural or synthetic) rubbers. The softer balata covers, althoughexhibiting enhanced playability properties, lack the durabilityproperties required for repetitive play.

Ionomeric resins are generally ionic copolymers of an olefin, such asethylene, and a metal salt of an unsaturated carboxylic acid, such asacrylic acid, methacrylic acid or maleic acid. In some instances, anadditional softening comonomer such as an acrylate can also be includedto form a terpolymer. The pendent ionic groups in the ionomeric resinsinteract to form ion-rich aggregates contained in a non-polar polymermatrix. The metal ions, such as sodium, zinc, magnesium, lithium,potassium, calcium, etc. are used to neutralize some portion of the acidgroups in the copolymer resulting in a thermoplastic elastomerexhibiting enhanced properties, i.e. improved durability, etc. for golfball construction over balata.

Broadly, the ionic copolymers comprise one or more alpha-olefins andfrom about 9 to about 20 weight percent of alpha, beta-ethylenicallyunsaturated mono- or dicarboxylic acid, the basic copolymer neutralizedwith metal ions to the extent desired. Usually, at least 20% of thecarboxylic acid groups of the copolymer are neutralized by the metalions (such as sodium, potassium, zinc, calcium, magnesium, and the like)and exist in the ionic state.

Suitable olefins for use in preparing the ionomeric resins includeethylene, propylene, butene-1, hexene-1, and the like. Unsaturatedcarboxylic acids include acrylic, methacrylic, ethacrylic,α-chloroacrylic, crotonic, maleic, fumaric, itaconic acids, and thelike. The ionomeric resins utilized in the golf ball industry aregenerally copolymers of ethylene with acrylic (i.e. Escor®) and/ormethacrylic (i.e. Surlyn®) acid. In addition, two or more types ofionomeric resins may be blended into the cover compositions in order toproduce the desired properties of the resulting golf balls.

Along this line, the properties of the cover compositions and/or theionomeric resins utilized in the golf ball industry vary according tothe type and amount of the metal cation, the molecular weight, thecomposition of the base resin (i.e. the nature and the relative contentof the olefin, the unsaturated carboxylic acid groups, etc.), the amountof acid, the degree of neutralization and whether additional ingredientssuch as reinforcement agents or additives are utilized. Consequently,the properties of the ionomer resins can be controlled and varied inorder to produce golf balls having different playing characteristics,such as differences in hardness, playability (i.e. spin, feel, click,etc.), durability (i.e. impact and/or cut resistance), and resilience(i.e. coefficient of restitution).

However, while there are currently more than fifty commercial grades ofionomers available from DuPont and Exxon with a wide range of propertieswhich vary according to the type and amount of metal cations, molecularweight, composition of the base resin (i.e. relative content of ethyleneand methacrylic and/or acrylic acid groups), the degree ofneutralization and additive ingredients such as reinforcement agents,etc., a great deal of research continues in order to develop golf ballcover compositions exhibiting not only the playability characteristicspreviously associated with the balata cover, but also the improvedimpact resistance and carrying distance properties produced by theionomeric resins. Thus, an object of the present invention is to providegolf ball cover compositions which, when utilized in golf ballconstruction, produce balls exhibiting improved travel distance whilemaintaining satisfactory playability and durability properties.

In enhancing the distance a golf ball will travel when hit, there are avariety of factors which are considered. The coefficient of restitution,along with ball size, weight and additional factors such as club headspeed, angle of trajectory, and ball aerodynamics (i.e., dimplepattern), generally determine the distance a ball will travel when hit.Since club head speed and the angle of trajectory are not factors easilycontrollable, particularly by golf ball manufacturers, the factors ofconcern among manufacturers are the coefficient of restitution and thesurface dimple pattern of the ball.

A golf ball's coefficient of restitution (C.O.R.) is the ratio of therelative velocity of the ball after direct impact to that before impact.One way to measure the coefficient of restitution is to propel a ball ata given speed against a hard massive surface, and measure its incomingvelocity and outgoing velocity. The coefficient of restitution isdefined as the ratio of the outgoing velocity to incoming velocity of arebounding ball and is expressed as a decimal. As a result, thecoefficient of restitution can vary from zero to one, with one beingequivalent to an elastic collision and zero being equivalent to aninelastic collision.

The coefficient of restitution of a one-piece golf ball is a function ofthe ball's composition. In a two-piece or a multi-layered golf ball, thecoefficient of restitution is a function of the core, the cover and anyadditional layer. While there are no United States Golf Association(U.S.G.A.) limitations on the coefficient of restitution values of agolf ball, the U.S.G.A. requires that the golf ball cannot exceed aninitial velocity of 255 feet/second. As a result, golf ballmanufacturers generally seek to maximize the coefficient of restitutionof a ball without violating the velocity limitation.

In various attempts to produce a high coefficient of restitution golfball exhibiting the enhanced travel distance desired, the golfingindustry has blended various ionomeric resins. However, many of theseblends do not exhibit the durability and playability characteristicsnecessary for repetitive play and/or the enhanced travel distancedesired.

The present invention is directed to the preparation of new cationneutralized ionomer resins containing relative high amounts of acid(i.e. greater than 16 weight percent acid, preferably from about 17 toabout 25 weight percent acid, and more preferably from about 18.5 toabout 21.5 weight percent acid) and partially neutralized with sodium,manganese, lithium, potassium, zinc, magnesium calcium and nickel ions.The new cation neutralized high acid ionomers produce, when blended andmelt processed according to the parameters set forth below, covercompositions exhibiting enhanced coefficient of restitution values whencompared to low acid ionomers, or blends of low acid ionomer resinscontaining 16 weight percent acid or less. The new high acid ionomercover compositions produce golf balls which exhibit properties ofenhanced carrying distance (i.e. possess higher coefficient ofrestitution values) over known ionomer blends such as those set forth inU.S. Pat. Nos. 4,884,814 and 4,911,451, without sacrificing desirablecharacteristics such as playability and/or durability.

Along this line, until relatively recently, all of the ionomer resinscommercially available contained at most 15 to 16 weight percentcarboxylic acid. In 1989, DuPont introduced a number of new high acidionomers and suggested that these new ionomers may have some use inpreviously known low acid ionomer applications such as the production ofshoe soles, box toes, bowling pins, golf balls, ski boots, auto trim,etc.

Furthermore, DuPont suggested in a research disclosure (E. I. DuPont deNemours & Co., Research Disclosure No. 297,003) that ionomers producedfrom polymers of ethylene acrylic acid or methacrylic acid containinggreater than 15 weight percent acid can be melt processed to producearticles (i.e. golf balls, foot wear, ski boots, cosmetic bottle capclosures and so on) with good properties (i.e. improved stiffness,hardness and clarity) when compared with ionomers with lower acidlevels.

However, not only has little information been provided concerning theacid levels and types of effective ionomers, particularly with respectto the art of golf ball manufacturing, it has been found that many covercompositions produced from polymers of ethylene/acrylic acid orethylene/methacrylic acid containing greater than 15 weight percent acidhave been dissatisfactory in that these compositions exhibit processingproblems or are generally short on distance and/or durability and thus,are not particularly commercially viable. Similar poor results have beenproduced with covers composed of blends of high and low acidethylene/acrylic acid or ethylene/methacrylic acid polymers and/orcovers produced from single high acid ionomers.

However, notwithstanding the above difficulties, it has been discoveredthat improved golf ball covers can be produced from specific blends ofhigh acid ionomers (i.e. ionomer resins containing greater than 16weight percent acid, preferably from about 17 to about 25 weight percentacid, and more preferably from about 18.5 to about 21.5 weight percentacid) which do not exhibit the processing, distance and/or durabilitylimitations demonstrated by the prior art.

In this regard, it has been found that blends of specific high acidionomer resins, particularly blends of sodium and zinc high acidionomers, as well as blends of sodium and magnesium high acid ionomers,extend, when utilized in golf ball cover construction, the range ofhardness beyond that previously obtainable while maintaining thebeneficial properties (i.e. durability, click, feel, etc.) of the softerlow acid ionomers disclosed in U.S. Pat. Nos. 4,884,814 and 4,911,451.These blends produce harder, stiffer golf balls having higher C.O.R.s,and thus longer distance. This discovery is the subject matter of U.S.application Ser. No. 776,803, filed on Oct. 15, 1991, and currentlycopending herewith.

The present invention is directed to the development of a number of newhigh acid ionomers, particularly new metal cation neutralized acrylicacid based high acid ionomer resins, which exhibit, when utilized forgolf ball cover construction, cover compositions having further improvedhardness and resilience (C.O.R.) properties. The new metal cationneutralized acrylic acid based high acid ionomer resins, as well asspecific blends of these resins, are particularly valuable in the fieldof golf ball production.

Furthermore, as a result of the development of a number of new acrylicacid based high acid ionomers neutralized to various extents by severaldifferent types of metal cations, such as by manganese, lithium,potassium, calcium and nickel cations, several new high acid ionomersand/or high acid ionomer blends besides sodium, zinc and magnesium highacid ionomers or ionomer blends are now available for golf ball coverproduction. It has been found that many of these new cation neutralizedhigh acid ionomer blends produce cover compositions exhibiting enhancedresilience (i.e. longer distance) due to synergies which occur duringprocessing. Consequently, the new metal cation neutralized acrylic acidbased high acid ionomer resins of the present invention may be blendedto produce substantially harder golf balls having higher C.O.R.'s thanthose produced by the low acid ionomer covers presently commerciallyavailable.

These and other objects and features of the invention will be apparentfrom the following description and from the claims.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to new metal cationneutralized high acid ionomer resins comprising a copolymer of greaterthan 16% by weight of an alpha, beta-unsaturated carboxylic acid(preferably from about 17% to about 25% by weight acid, and morepreferably from about 18.5% to about 21.5% by weight acid) and analpha-olefin, of which about 10% to about 90% of the carboxyl groups ofthe copolymer are neutralized with a metal cation selected from thegroup consisting of manganese, lithium, potassium, calcium and nickel.

In another aspect, the invention relates to metal cation neutralizedhigh acid ionomer resins comprising a copolymer of about 20% by weightof an alpha, beta-unsaturated carboxylic acid (preferably acrylic acid)and an olefin (preferably ethylene), of which about 10% to about 90% ofthe carboxyl groups of the copolymer are neutralized with a metal cationselected from the group consisting of manganese, lithium, potassium,calcium and nickel.

In a further aspect, the present invention concerns a metal cationneutralized high acid ionomer resins comprising a copolymer of about 20%by weight acrylic acid with the remainder, or balance, thereof beingethylene, of which 10% to 90% of the carboxyl groups of the copolymerare neutralized with a metal cation selected from the group consistingof manganese, lithium, potassium, magnesium, calcium and nickel.

In still another aspect, the invention is directed to a metal cationneutralized high acid ionomer resin comprising a copolymer of about 20%by weight acrylic acid and the remainder ethylene, of which 10% to 90%of the carboxyl groups of the copolymer are neutralized with a metalcation selected from the group consisting of sodium, manganese, lithium,potassium, zinc, magnesium, calcium and nickel. The metal cationneutralized high acid ionomer resin produces, when blended and moldedaround solid or wound cores to form a cover composition, golf ballsexhibiting enhanced resilience (i.e. improved C.O.R.) without adverselyaffecting the ball's playability and/or durability characteristics.

In an additional aspect, the invention relates to a method for producingmetal cation neutralized high acid ionomer resins comprising the stepsof providing a copolymer comprised of greater than 16% by weight of analpha, beta-unsaturated carboxylic acid and an olefin; and neutralizingfrom about 10% to about 90% of the carboxylic acid groups of thecopolymer with a metal cation selected from the group consisting ofmanganese, lithium, potassium, calcium and nickel. The metal cationneutralized high acid ionomer resins produced by this method are alsoprovided.

In another aspect, the present invention concerns a process forproducing metal cation neutralized acrylic acid based high acid ionomerresins comprising the steps of providing a copolymer made of about 20%by weight of acrylic acid and the balance ethylene, and neutralizingfrom about 10% to about 90% of the carboxylic acid groups of thecopolymer with a metal cation selected from the group consisting ofmanganese, lithium, potassium, magnesium, calcium and nickel. The newmetal cation neutralized high acid ionomer resins produced by thismethod are also provided.

In still a further aspect, the invention is directed to a golf ballcomprising a core and a cover, wherein the cover is comprised of a metalcation neutralized high acid ionomer resin which is a copolymer ofgreater than 16% by weight of an alpha, beta-unsaturated carboxylicacid, (preferably from about 17% to about 25% by weight acid, and morepreferably from about 18.5% to about 21.5% by weight acid) and anolefin, of which 10% to 90% of the carboxyl groups of the copolymer areneutralized with a metal cation selected from the group consisting ofmanganese, lithium, potassium, calcium and nickel. In addition, thecover may contain of one or more additional ingredients such aspigments, dyes, U.V. absorbers and optical brighteners.

In another further aspect, the invention relates to a golf ballcomprising a core and a cover, wherein the cover is comprised of a metalcation neutralized ionomer resin which is a copolymer of about 20% byweight of an acrylic acid and the remainder ethylene, of which 10% to90% of the carboxyl groups of the acrylic acid/ethylene copolymer areneutralized with a metal cation selected from the group consisting ofmanganese, lithium, potassium, magnesium, calcium and nickel. The coreis generally a solid core, and additional ingredients such as pigments,dyes, U.V. absorbers and optical brighteners may be included in thecover.

In a further additional aspect, the invention is directed to a golf ballcomprising a core and a cover, wherein the cover is a blend of two ormore metal cation neutralized high acid ionomer resins, each ionomerresin comprised of about 20% by weight of acrylic acid and the remainderethylene, of which about 10% to about 90% of the carboxyl groups of thecopolymer are neutralized with a metal cation. The metal cation of eachresin is a cation selected from the group consisting of sodium,manganese, lithium, potassium, zinc, magnesium, calcium and nickel. Inthis regard, diblends consisting of sodium/manganese, sodium/lithium,sodium/zinc, sodium/magnesium, sodium/calcium, manganese/potassium,lithium/zinc, lithium/magnesium, lithium/calcium, andpotassium/magnesium neutralized 20% acrylic acid/ethylene ionomer resinsand triblends consisting of zinc/lithium/potassium, sodium/zinc/lithium,sodium/manganese/calcium, sodium/potassium/manganese, andsodium/potassium/magnesium neutralized 20% acrylic acid/ethylene ionomerresins are the more preferred blends which comprise the cover componentof the invention.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the development of a number of newmetal cation neutralized high acid ionomers. In addition, the presentinvention relates to the use of these new metal cation neutralized highacid ionomers, and/or blends thereof, for the purpose of producing golfball covers exhibiting enhanced resilience and/or hardnesscharacteristics.

In this regard, several new metal cation neutralized high acid ionomerresins have been produced by neutralizing, to various extents, high acidcopolymers of an alpha-olefin and an alpha, beta-unsaturated carboxylicacid with a wide variety of different metal cation salts. Moreparticularly, it has been found that numerous new metal cationneutralized high acid ionomer resins can be obtained by reacting a highacid copolymer (i.e. a copolymer containing greater than 16% by weightacid, preferably from about 17 to about 25 weight percent acid, and morepreferably about 20 weight percent acid), with a metal cation saltcapable of ionizing or neutralizing the copolymer to the extent desired(i.e. from about 10% to 90%).

The base copolymer is made up of greater than 16% by weight of an alpha,beta-unsaturated carboxylic acid and an alpha-olefin. Optionally, asoftening comonomer can be included in the copolymer. Generally, thealpha-olefin has from 2 to 10 carbon atoms and is preferably ethylene,and the unsaturated carboxylic acid is a carboxylic acid having fromabout 3 to 8 carbons. Examples of such acids include acrylic acid,methacrylic acid, ethacrylic acid, chloroacrylic acid, crotonic acid,maleic acid, fumaric acid, and itaconic acid, with acrylic acid beingpreferred.

The softening comonomer that can be optionally included in the inventionmay be selected from the group consisting of vinyl esters of aliphaticcarboxylic acids wherein the acids have 2 to 10 carbon atoms, vinylethers wherein the alkyl groups contains 1 to 10 carbon atoms, and alkylacrylates or methacrylates wherein the alkyl group contains 1 to 10carbon atoms. Suitable softening comonomers include vinyl acetate,methyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, butyl acrylate, butyl methacrylate, or the like.

Consequently, examples of a number of copolymers suitable for use in theinvention include, but are not limited to, high acid embodiments of anethylene/acrylic acid copolymer, an ethylene/methacrylic acid copolymer,an ethylene/itaconic acid copolymer, an ethylene/maleic acid copolymer,an ethylene/methacrylic acid/vinyl acetate copolymer, anethylene/acrylic acid/vinyl alcohol copolymer, etc. The base copolymerbroadly contains greater than 16% by weight unsaturated carboxylic acid,from about 30 to about 83% by weight ethylene and from 0 to about 40% byweight of a softening comonomer. Preferably, the copolymer containsabout 20% by weight unsaturated carboxylic acid and about 80% by weightethylene. Most preferably, the copolymer contains about 20% acrylic acidwith the remainder being ethylene.

Along these lines, examples of the preferred high acid base copolymerswhich fulfill the criteria set forth above, are a series ofethylene-acrylic copolymers which are commercially available from TheDow Chemical Company, Midland, Mich., under the “Primacor” designation.These high acid base copolymers exhibit the typical properties set forthbelow in Table 1.

TABLE 1 Typical Properties of Primacor Ethylene-Acrylic Acid CopolymersMELT TENSILE FLEXURAL VICAT PERCENT DENSITY, INDEX, YD. ST MODULUS SOFTPT SHORE D GRADE ACID glcc g/10 min (psi) (psi) (° C.) HARDNESS ASTMD-792 D-1238 D-638 D-790 D-1525 D-2240 5980 20.0 0.958  300.0 — 4800 4350 5990 20.0 0.955 1300.0 650 2600 40 42 5990 20.0 0.955 1300.0 650 320040 42 5981 20.0 0.960  300.0 900 3200 46 48 5981 20.0 0.960  300.0 9003200 46 48 5983 20.0 0.958  500.0 850 3100 44 45 5991 20.0 0.953 2600.0635 2600 38 40 ¹The Melt Index values are obtained according to ASTMD-1238, at 190° C.

Due to the high molecular weight of the Primacor 5981 grade of theethylene-acrylic acid copolymer, this copolymer is the more preferredgrade utilized in the invention.

The metal cation salts utilized in the invention are those salts whichprovide the metal cations capable of neutralizing, to various extents,the carboxylic acid groups of the high acid copolymer. These includeacetate, oxide or hydroxide salts of lithium, calcium, zinc, sodium,potassium, nickel, magnesium, and manganese.

Examples of such lithium ion sources are lithium hydroxide monohydrate,lithium hydroxide, lithium oxide and lithium acetate. Sources for thecalcium ion include calcium hydroxide, calcium acetate and calciumoxide. Suitable zinc ion sources are zinc acetate dihydrate and zincacetate, a blend of zinc oxide and acetic acid. Examples of sodium ionsources are sodium hydroxide and sodium acetate. Sources for thepotassium ion include potassium hydroxide and potassium acetate.Suitable nickel ion sources are nickel acetate, nickel oxide and nickelhydroxide. Sources of magnesium include magnesium oxide, magnesiumhydroxide, magnesium acetate. Sources of manganese include manganeseacetate and manganese oxide.

The new metal cation neutralized high acid ionomer resins of theinvention are produced by reacting the high acid base copolymer withvarious amounts of the metal cation salts above the crystalline meltingpoint of the copolymer, such as at a temperature from about 200° F. toabout 500° F., preferably from about 250° F. to about 350° F. under highshear conditions at a pressure of from about 100 psi to 10,000 psi.Other well known blending techniques may also be used. The amount ofmetal cation salt utilized to produce the new metal cation neutralizedhigh acid based ionomer resins is the quantity which provides asufficient amount of the metal cations to neutralize the desiredpercentage of the carboxylic acid groups in the high acid copolymer. Theextent of neutralization is generally from about 10% to about 90%.

As indicated more specifically in Example 1 below, a number of new typesof metal cation neutralized high acid ionomers can be obtained from theprocess of this invention. These include new high acid ionomer resinsneutralized to various extents with manganese, lithium, potassium,calcium and nickel cations. In addition, when a high acidethylene/acrylic acid copolymer is utilized as the base copolymercomponent of the invention and this component is subsequentlyneutralized to various extents with the metal cation salts producingacrylic acid based high acid ionomer resins neutralized with cationssuch as sodium, potassium, lithium, zinc, magnesium, manganese, calciumand nickel, several new cation neutralized acrylic acid based high acidionomer resins are produced.

When compared to low acid versions of similar cation neutralized ionomerresins, the new metal cation neutralized high acid ionomer resinsexhibit enhanced hardness, modulus and resilience characteristics. Theseare properties that are particularly desirable in a number ofthermoplastic fields, including the field golf ball manufacturing.

When utilized in golf ball cover construction, it has been found thatthe new acrylic acid based high acid ionomers extend the range ofhardness beyond that previously obtainable while maintaining thebeneficial properties (i.e. durability, click, feel, etc.) of the softerlow acid ionomer covered balls, such as balls produced utilizing the lowacid ionomers disclosed in U.S. Pat. Nos. 4,884,814 and 4,911,451, andthe recently produced high acid blends disclosed in U.S. applicationSer. No. 776,803.

Moreover, as a result of the development of a number of new acrylic acidbased high acid ionomer resins neutralized to various extents by severaldifferent types of metal cations, such as manganese, lithium, potassium,calcium and nickel cations, several new ionomers or ionomer blends arenow available for golf ball production. By using the high acid ionomerresins of the present invention, harder, stiffer golf balls havinghigher C.O.R.s, and thus longer distance, can be obtained.

Examples of existing high acid methacrylic acid based ionomers includeSurlyn® AD-8422 (sodium cation), Surlyn® 8162 (zinc cation), Surlyn®SEP-503-1 (an experimental zinc cation), and Surlyn® SEP-503-2 (anexperimental magnesium cation). According to DuPont, all of theseionomers contain from about 18.5% to about 21.5% by weight methacrylicacid.

More particularly, Surlyn® AD-8422, is currently commercially availablefrom DuPont in a number of different grades (i.e. AD-8422-2, AD-8422-3,AD-8422-5, etc.) based upon differences in melt index. According toDuPont, Surlyn® AD-8422 offers the following general properties whencompared to Surlyn® 8920 the stiffest, hardest of all of the low acidgrades (referred to as “hard” ionomers in U.S. Pat. No. 4,884,814):

TABLE 2 LOW ACID HIGH ACID (15 wt % Acid) (>20 wt % Acid) SURLYN ®SURLYN ® SURLYN ® 8920 8422-2 8422-3 IONOMER Cation Na Na Na Melt Index1.2 2.8 1.0 Sodium, Wt % 2.3 1.9 2.4 Base Resin MI 60 60 60 MP¹, ° C. 8886 85 FP¹, ° C. 47 48.5 45 COMPRESSION MOLDING² Tensile Break, psi 43504190 5330 Yield, psi 2880 3670 3590 Elongation, % 315 263 289 Flex Mod,K psi 53.2 76.4 88.3 Shore D hardness 66 67 68 ¹DSC second heat, 10°C./min heating rate. ²Samples compression molded at 150° C. annealed 24hours at 60° C. 8422-2, 8422-3 were homogenized at 190° C. beforemolding.

In comparing Surlyn® 8920 to Surlyn® 8422-2 and Surlyn® 8422-3, it isnoted that the high acid Surlyn® 8422-2 and 8422-3 ionomers have ahigher tensile yield, lower elongation, slightly higher Shore D hardnessand much higher flexural modulus. Surlyn® 8920 contains 15 weightpercent methacrylic acid and is 59% neutralized with sodium.

In addition, Surlyn® SEP-503-1 (an experimental zinc cation neutralizedhigh acid methacrylic acid based ionomer resin) and Surlyn® SEP-503-2(an experimental magnesium cation neutralized high acid methacrylic acidbased ionomer resin) are high acid zinc and magnesium versions of theSurlyn® AD 8422 high acid ionomers. When compared to the Surlyn® AD 8422high acid ionomers, the Surlyn® SEP-503-1 and SEP-503-2 ionomers can bedefined as follows:

TABLE 3 Surlyn ® Ionomer Ion Melt Index Neutralization % AD 8422-3 Na1.0 45 SEP 503-1 Zn 0.8 38 SEP 503-2 Mg 1.8 43

Furthermore, Surlyn® 8162 is a zinc cation neutralized methacrylic acidbased high acid ionomer resin containing approximately 20% by weight(i.e. 18.5-21.5% weight) methacrylic acid copolymer that has been 30-70%neutralized. Surlyn® 8162 is currently commercially available fromDuPont.

For comparison purposes, examples of commercially available low acidmethacrylic acid based ionomer resins are set forth below. These aremany of the “hard” ionomers utilized in the cover composition disclosedin U.S. Pat. No. 4,884,814. Along this line, the low acid ionomer resincover compositions disclosed in the '814 patent are generally consideredto be among the best prior art methacrylic acid based cover compositionscurrently available from Spalding & Evenflo Companies, Inc., theassignee of the present application and U.S. application Ser. No.776,803.

TABLE 4 ASTM D 8940 9910 8920 Cation Type Sodium Zinc Sodium Melt flowindex, D-1238 2.8 0.7 0.9 gms/10 min Specific Gravity, D-792 0.95 0.970.95 g/cm³ Hardness, Shore D D-2240 66 64 66 Tensile Strength, D-638(4.8) (3.6) (5.4) (kpsi), MPa 33.1 24.8 37.2 Elongation, % D-638 470 290350 Flexural Modulus, D-790 (51) (48) (55) (kpsi) MPa 350 330 380Tensile Impact (23° C.) D-18225 1020 1020 865 KJ/m₂ (ft.- lbs./in²)(485) (485) (410) Vicat Temperature, ° C. D-1525 63 62 58 % WeightMethacrylic 15 15 15 acid (MAA) % of Acid Groups 29 58 59 CationNeutralized ASTM D 8528 9970 9730 Cation Type Sodium Zinc Zinc Melt flowindex, D-1238 1.3 14.0 1.6 gms/10 min Specific Gravity, D-792 0.94 0.950.95 g/cm³ Hardness, Shore D D-2240 60 62 63 Tensile Strength, D-638(4.2) (3.2) (4.1) (kpsi), MPa 29.0 22.0 28.0 Elongation, % D-638 450 460460 Flexural Modulus, D-790 (32) (28) (30) (kpsi) MPa 220 190 210Tensile Impact (23° C.) D-18225 1160 760 1240 KJ/m₂ (ft.-lbs./in²) (550)(360) (590) Vicat Temperature, ° C. D-1525 73 61 73 % Weight Methacrylic10 15 12 acid (MAA) % of Acid Groups 54 22 38 Cation Neutralized

Examples of existing high acid acrylic acid based ionomer resins includethe Escor® or the Iotek acrylic acid based high acid ionomers recentlyexperimentally produced by Exxon. In this regard, Escor®, or Iotek, 959is a sodium ion neutralized ethylene-acrylic acid copolymer and Escor®,or Iotek, 960 is a zinc neutralized ethylene-acrylic acid copolymer.According to Exxon, Ioteks 959 and 960 contain from about 19.0 to about21.0% by weight acrylic acid with approximately 30 to about 70 percentof the acid groups neutralized with sodium and zinc ions respectfully.The physical properties of these high acid acrylic acid based ionomersare as follows:

TABLE 5 ESCOR ® ESCOR ® PROPERTY (IOTEK) 959 (IOTEK) 960 Melt Index,g/10 min 2.0 1.8 Cation Sodium Zinc Melting Point, ° F. 172 174 VicatSoftening Point,° F. 130 131 TenBile @ Break, psi 4600 3500 Elongation @Break, % 325 430 Hardness, Shore D 66 57 Flexural Modulus, psi 66,00027,000

For comparison purposes, examples of commercially available low acidacrylic acid based ionomer resins, such as these utilized in U.S. Pat.No. 4,911,451 are set forth below.

TABLE 6 Typical Properties of Low Acid Escor ® (Iotek) Ionomers ResinASTM Properties Method Units 4000 4010 8000 8020 Cation type zinc zincsodium sodium Melt index D-1238 g/ 2.5 1.5 0.8 1.6 10 min. DensityD-1505 kg/m³ 963 963 954 960 Melting Point D-3417 ° C. 90 90 90 87.5Crystallization D-3417 ° C. 62 64 56 53 Point Vicat Softening D-1525 °C. 62 63 61 64 Point % Weight Acrylic 16 — 11 — Acid % of Acid Groups 30— 40 — Cation Neutralized Plaque Properties (3 mm thick, compressionASTM molded) Method Units 4000 4010 8000 8020 Tensile at Break D-638 MPa24 26 36 31.5 Yield point D-638 MPa none none 21 21 Elongation at D-638% 395 420 350 410 break 1% Secant D-638 MPa 160 160 300 350 modulusShore Hardness D D-2240 — 55 55 61 58 Resin ASTM Properties Method Units8030 7010 7020 7030 Cation type sodium zinc zinc zinc Melt index D-1238g/ 2.8 0.8 1.5 2.5 10 min. Density D-1505 kg/m³ 960 960 960 960 MeltingPoint D-3417 ° C. 87.5 90 90 90 Crystallization D-3417 ° C. 55 — — —Point Vicat Softening D-1525 ° C. 67 60 63 62.5 Point % Weight Acrylic —— — — Acid % of Acid Groups — — — — Cation Neutralized Plaque Properties(3 mm thick, compression ASTM molded) Method Units 8030 7010 7020 7030Tensile at Break D-638 MPa 28 38 38 38 Yield point D-638 MPa 23 nonenone none Elongation at D-638 % 395 500 420 395 break 1% Secant D-638MPa 390 — — — modulus Shore Hardness D D-2240 — 59 57 55 55

According to the present invention, it has been found that when theabove indicated new metal cation neutralized acrylic acid based highacid ionomers, are processed according to the parameters set forth belowto produce the covers of multi-layered golf balls, the resulting golfballs will travel further than previously known low acid ionomer resincovers and/or covers produced from high acid ionomers and/or highacid/low acid ionomer blends due to the balls' enhanced coefficient ofrestitution values. This is particularly important in that animprovement of 0.001 in C.O.R. generally relates to our improvement ofabout 0.2 to 0.5 yards in travel distance. In addition, the resultinggolf balls maintain the playability and durability characteristicsexhibited by known low-acid ionomer resin covered balls.

When blends of two of the above indicated metal cation neutralizedacrylic acid high acid ionomers are used (i.e. “dibends”), the ratio ofone type of metal cation neutralized acrylic acid high acid ionomer toanother is generally from about 75% to about 25% and from about 25% toabout 75%. In addition, “triblends” can also be formulated utilizing thenew metal cation neutralized acrylic acid based high acid ionomers ofthe present invention. The general ratio for such “triblends” is33.33%/33.33%/33.33% by weight.

Additional compatible additive materials may also be added to thecompositions of the present invention, such as dyes (for example,Ultramarine Blue sold by Whitaker, Clark, and Daniels of SouthPainsfield, N.J.), and pigments, i.e. white pigments such as titaniumdioxide (for example Unitane 0-110) zinc oxide, and zinc sulfate, aswell as fluorescent pigments. As indicated in U.S. Pat. No. 4,884,814,the amount of pigment and/or dye used in conjunction with the polymericcover composition depends on the particular base ionomer mixtureutilized and the particular pigment and/or dye utilized. Theconcentration of the pigment in the polymeric cover composition can befrom about 1% to about 10% as based on the weight of the base ionomermixture. A more preferred range is from about 1% to about 5% as based onthe weight of the base ionomer mixture. The most preferred range is fromabout 1% to about 3% as based on the weight of the base ionomer mixture.The most preferred pigment for use in accordance with this invention istitanium dioxide.

Moreover, since these are various hues of white, i.e. blue white, yellowwhite, etc., trace amounts of blue pigment may be added to the coverstock composition to impart a blue white appearance thereto. However, ifdifferent hues of the color white are desired, different pigments can beadded to the cover composition at the amounts necessary to produce thecolor desired.

In addition, it is within the purview of this invention to add to thecover compositions of this invention compatible materials which do notaffect the basic novel characteristics of the composition of thisinvention. Among such materials are antioxidants (i.e. Santonox R),antistatic agents, stabilizers and processing aids. The covercompositions of the present invention may also contain softening agents,such as plasticizers, etc., and reinforcing materials such as glassfibers and inorganic fillers, as long as the desired properties producedby the golf ball covers of the invention are not impaired.

Furthermore, optical brighteners, such as those disclosed in U.S. Pat.No. 4,679,795, may also be included in the cover composition of theinvention. Examples of suitable optical brighteners which can be used inaccordance with this invention are Uvitex OB as sold by the Ciba-GeigyChemical Company, Ardaley, N.Y. Uvitex OB is thought to be 2,5-Bis(5-tert-butyl-2-benzoxazoly) thiopene. Examples of other opticalbrighteners suitable for use in accordance with this invention are asfollows: Leucopure EGM as sold by Sandoz, East Hanover, N.J. 07936.Leucopure EGM is thought to be7-(2h-naphthol(1,2-d)-triazol-2yl)-3phenyl-coumarin. Phorwhite K-20G2 issold by Mobay Chemical Corporation, P.O. Box 385, Union Metro Park,Union, N.J. 07083, and is thought to be a pyrazoline derivative,Eastobrite OB-1 as sold by Eastman Chemical Products, Inc. Kingsport,Tenn., is thought to be 4,4-Bis(-benzoxaczoly)stilbene. Theabove-mentioned Uvitex and Eastobrite OB-1 are preferred opticalbrighteners for use in accordance with this invention.

Moreover, since many optical brighteners are colored, the percentage ofoptical brighteners utilized must not be excessive in order to preventthe optical brightener from functioning as a pigment or dye in its ownright.

The percentage of optical brighteners which can be used in accordancewith this invention is from about 0.01% to about 0.5% as based on theweight of the polymer used as a cover stock. A more preferred range isfrom about 0.05% to about 0.25% with the most preferred range from about0.10% to about 0.020% depending on the optical properties of theparticular optical brightener used and the polymeric environment inwhich it is a part.

Generally, the additives are admixed with a ionomer to be used in thecover composition to provide a masterbatch (M.B.) of desiredconcentration and an amount of the masterbatch sufficient to provide thedesired amounts of additive is then admixed with the copolymer blends.

The cover compositions of the present invention may be producedaccording to conventional melt blending procedures. In this regard, theabove indicated high acid ionomeric resins are blended along with themasterbatch containing the desired additives in a Banbury type mixer,two-roll mill, or extruded prior to molding. The blended composition isthen formed into slabs or pellets, etc. and maintained in such a stateuntil molding is desired. Alternatively a simple dry blend of thepelletized or granulated resins and color masterbatch may be preparedand fed directly into the injection molding machine where homogenizationoccurs in the mixing section of the barrel prior to injection into themold. If necessary, further additives such as an inorganic filler, etc.,may be added and uniformly mixed before initiation of the moldingprocess.

Moreover, golf balls of the present invention can be produced by moldingprocesses currently well known in the golf ball art. Specifically, thegolf balls can be produced by injection molding or compression moldingthe novel cover compositions about wound or solid molded cores toproduce a golf ball having a diameter of about 1.680 inches or greaterand weighing about 1.620 ounces. The standards for both the diameter andweight of the balls are established by the United States GolfAssociation (U.S.G.A.). Although both solid core and wound cores can beutilized in the present invention, as a result of their lower cost andsuperior performance, solid molded cores are preferred over wound cores.

Conventional solid cores are typically compression molded from a slug ofuncured or lightly cured elastomer composition comprising a high ciscontent polybutadiene and a metal salt of an α, β, ethylenicallyunsaturated carboxylic acid such as zinc mono or diacrylate ormethacrylate. To achieve higher coefficients of restitution in the core,the manufacturer may include a small amount of a metal oxide such aszinc oxide. In addition, larger amounts of metal oxide than those thatare needed to achieve the desired coefficient may be included in orderto increase the core weight so that the finished ball more closelyapproaches the U.S.G.A. upper weight limit of 1.620 ounces. Othermaterials may be used in the core composition including compatiblerubbers or ionomers, and low molecular weight fatty acids such asstearic acid. Free radical initiator catalysts such as peroxides areadmixed with the core composition so that on the application of heat andpressure, a complex curing or cross-linking reaction takes place.

The term “solid cores” as used herein refers not only to one piece coresbut also to those cores having a separate solid layer beneath the coverand above the core as in U.S. Pat. No. 4,431,193, and other multilayerand/or non-wound cores (such as those described in U.S. Pat. No.4,848,770).

Wound cores are generally produced by winding a very large elasticthread around a solid or liquid filled balloon center. The elasticthread is wound around the center to produce a finished core of about1.4 to 1.6 inches in diameter, generally. Since the core material is notan integral part of the present invention, a detailed discussionconcerning the specific types of core materials which may be utilizedwith the cover compositions of the invention are not specifically setforth herein. In this regard, the cover compositions of the inventionmay be used in conjunction with any standard golf ball core.

As indicated, the golf balls of the present invention may be produced byforming covers consisting of the compositions of the invention aroundcores by conventional molding processes. For example, in compressionmolding, the cover composition is formed via injection at about 380° F.to about 450° F. into smooth surfaced hemispherical shells which arethen positioned around the core in a dimpled golf ball mold andsubjected to compression molding at 200-300° F. for 2-10 minutes,followed by cooling at 50-70° F. for 2-10 minutes, to fuse the shellstogether to form an unitary ball. In addition, the golf balls may beproduced by injection molding, wherein the cover composition is injecteddirectly around the core placed in the center of a golf ball mold for aperiod of time at a mold temperature of from 50° F. to about 100° F.After molding the golf balls produced may undergo various furtherfinishing steps such as buffing, painting, and marking as disclosed inU.S. Pat. No. 4,911,451.

The present invention is further illustrated by the following examplesin which the parts of the specific ingredients are by weight (pbw). Itis to be understood that the present invention is not limited to theexamples, and various changes and modifications may be made in theinvention without departing from the spirit and scope thereof.

EXAMPLES

By blending the ingredients set forth in the Tables below, a series ofnew metal cation neutralized high acid ionomer resins and golf ballcover formulations containing these resins were produced. Finished golfballs were prepared using the cover compositions of the presentinvention, controls and comparative cover compositions by positioning asolid preformed cross-linked polybutadiene core in an injection moldingcavity in such a manner to permit the uniform injection of the selectedcover composition over each core. Along this line, the coverformulations were injection molded at about 400° F. around identicalsolid type cores having a finished diameter of 1.545 inches to producegolf balls approximately 1.680 inches in diameter having a normal coverthickness of 0.0675 inches. All materials were molded under essentiallyidentical conditions. The properties of coefficient of restitution(C.O.R.) of the molded and finished balls, Shore D hardness, cold crackresistance, spin rates, etc. for the cover compositions were thendetermined.

In conducting the comparative prior art testing, Escor® 4000/7030 andEscor® 900/8000 ionomers were utilized. In this regard, blends of Escor®4000/7030 and Escor® 900/8000 (i.e. the subject of U.S. Pat. No.4,911,451) are considered by the inventors to be generally among thebest prior art cover compositions concerning ethylene-acrylic acidionomer (low acid) blends.

The data for each example represents the average data for one dozenballs produced according to the desired manner. The properties weremeasured according to the following parameters:

Coefficient of restitution (C.O.R.) was measured by firing the resultinggolf ball in an air cannon at a velocity of 125 feet per second againsta steel plate which is positioned 12 feet from the muzzle of the cannon.The rebound velocity was then measured. The rebound velocity was dividedby the forward velocity to give the coefficient of restitution.

Shore hardness was measured in accordance with ASTM Test D-2240.

Cold cracking resistance was measured by firing balls from an aircannon, 5 blows at 165 feet/sec, after the balls had been conditionedfor 24 hours at −10° F. After allowing the balls to equilibrate to roomtemperature the balls are inspected for cover cracking.

The spin rate of the golf ball was measured by striking the resultinggolf balls with a pitching wedge or 9-iron wherein the club-head speedis about 80 feet per second and the ball is launched at an angle of 26to 34 degrees with an initial velocity of about 110-115 feet per second.The spin rate was measured by observing the rotation of the ball inflight using stop action Strobe photography.

Example 1

Preparation of Acrylic Acid Based High Acid Ionomers

A number of new cation neutralized acrylic acid based high acid ionomerresins were prepared utilizing as the copolymer of an olefin and analpha, beta-unsaturated carboxylic acid, a 20 weight percent acrylicacid/ethylene copolymer produced by The Dow Chemical Company, Midland,Mich. under the designation “Primacor 5981.” According to The DowChemical Company, Primacor 5981 has a melt index (at 190° C., 2150 g) of300 g/10 min. The carboxylic acid groups present in the 20 weightpercent acrylic acid/ethylene copolymer were neutralized to variousweight percentages by a number of different metal cation salts resultingin the production of several new thermoplastic elastomers exhibitingenhanced properties for golf ball cover production. Due to differencesin the nature of the cation salts, the amount of cation salts utilized,etc., the new high acid ionomer resins produced differed substantiallyin the extent of neutralization and in melt indices, as well as inresilience (i.e. C.O.R.) and hardness values.

For the purpose of determining the weight percent of neutralization ofthe carboxylic acid groups in the acrylic acid/ethylene copolymer afterreacting with various cation salts, it was assumed that 1 mole of sodium(Na⁺), potassium (K⁺), and lithium (Li⁺) neutralized one mole of acrylicacid, and that one mole of zinc (Zn²⁺), magnesium (Mg²⁺), manganese(Mn²⁺), calcium (Ca²⁺) and nickel (Ni²⁺) neutralized two moles ofacrylic acid. The calculations of neutralization were based upon anacrylic acid molecular weight of 79 g/m, giving 0.2778 moles per 100grams of copolymer.

As indicated below in Table 7, the various cation salts were added invariable amounts to the 20 weight percent acrylic acid/ethylenecopolymer in order to determine the optimal level of neutralization foreach of the cations. In Table 7, NaOH refers to sodium hydroxide(formula weight of 40). MnAc refers to manganese acetate tetrahydratehaving a formula weight of 245. LiOH is lithium hydroxide, fwt=24. KOHis potassium hydroxide, fwt=56. ZnAc is zinc acetate dihydrate,fwt=219.5. MgAc is magnesium acetate tetrahydrate, fwt=214.4. CaAc iscalcium acetate, fwt=158. MgO is magnesium oxide, fwt=40.3. NiAc isnickel acetate, fwt=176.8. All of these cation salts are solids at roomtemperature.

The specific cation salts were added in differing amounts with the 20weight percent acrylic acid/ethylene copolymer (i.e. the Primacor 5981)to an internal mixer (Banbury type) for the neutralization reaction. Theonly exception was calcium acetate, which, due to problems encounteredin solid form, was added as a 30 wt-% solution in water.

In the neutralization reaction, the cation salts solubilized in thePrimacor 5981 acrylic acid/ethylene copolymer above the melting point ofthe copolymer and a vigorous reaction took place with a great deal offoaming occurring as the cation reacted with the carboxylic acid groupsof the acrylic acid/ethylene copolymer and the volatile by-products ofwater (in the case of oxides or hydroxides) or acetic acid (whenacetates are used) were evaporated. The reaction was continued untilfoaming ceased (i.e. about 30-45 minutes at 250-350° F.), and the batchwas removed from the Banbury mixer. Mixing continued of the batchobtained from the mixer on a hot two-roll mill (175-250° F.) to completethe neutralization reaction. The extent of the reaction was monitored bymeasuring melt flow index according to ASTM D-1238-E. As indicatedbelow, the neutralized products exhibited drastically differentproperties depending upon the nature and amount of the cation saltsutilized.

TABLE 7 Shore D Formulation wt-% wt-% Melt Hard- No. Cation SaltNeutralization Index C.O.R. ness 1 (NaOH) 6.98 67.5 0.9 .804 71 2 (NaOH)5.66 54.0 2.4 .808 73 3 (NaOH) 3.84 35.9 12.2 .812 69 4 (NaOH) 2.91 27.017.5 .812 (brittle) 5 (MnAc) 19.6 71.7 7.5 .809 73 6 (MnAc) 23.1 88.33.5 .814 77 7 (MnAc) 15.3 53.0 7.5 .810 72 8 (MnAc) 26.5 106 0.7 .813(brittle) 9 (LiOH) 4.54 71.3 0.6 .810 74 10 (LiOH) 3.38 52.5 4.2 .818 7211 (LiOH) 2.34 35.9 18.6 .815 72 12 (KOH) 5.30 36.0 19.3 Broke 70 13(KOH) 8.26 57.9 7.18 .804 70 14 (KOH) 10.7 77.0 4.3 .801 67 15 (ZnAc)17.9 71.5 0.2 .806 71 16 (ZnAc) 13.9 53.0 0.9 .797 69 17 (ZnAc) 9.9136.1 3.4 .793 67 18 (MgAc) 17.4 70.7 2.8 .814 74 19 (MgAc) 20.6 87.1 1.5.815 76 20 (MgAc) 13.8 53.8 4.1 .814 74 21 (CaAc) 13.2 69.2 1.1 .813 7422 (CaAc) 7.12 34.9 10.1 .808 70 Controls: 50/50 Blend of Ioteks8000/7030 C.O.R. = .810/65 Shore D Hardness DuPont High Acid Surlyn ®8422 (Na) C.O.R. = .811/70 Shore D Hardness DuPont High Acid Surlyn ®8162 (Zn) C.O.R. = .807/65 Shore D Hardness Exxon High Acid Iotek EX-960(Zn) C.O.R. = .796/65 Shore D Hardness Wt-% Wt-% Melt Formulation No.Cation Salt Neutralization Index C.O.R. 23 (MgO) 2.91 53.5 2.5 .813 24(MgO) 3.85 71.5 2.8 .808 25 (MgO) 4.76 89.3 1.1 .809 26 (MgO) 1.96 35.77.5 .815 Control for Formulations 23-26 is 50/50 Iotek 8000/7030, C.O.R.= .814, Formulation 26 C.O.R. was normalized to that control accordinglyFormulation Wt-% Wt-% Melt Shore D No. Cation Salt Neutralization IndexC.O.R. Hardness 27 (NiAc) 13.04 61.1 0.2 .802 71 28 (NiAc) 10.71 48.90.5 .799 72 29 (NiAc) 8.26 36.7 1.8 .796 69 30 (NiAc) 5.66 24.4 7.5 .78664 Control for Formulation Nos. 27-30 is 50/50 Iotek 8000/7030, C.O.R. =.807

As indicated in Table 7, a number of the new cation neutralized acrylicacid based high acid ionomer resins exhibited C.O.R. and Shore Dhardness values greater than that exhibited by a 50/50 blend of theIotek low acid acrylic acid based hard ionomer resins, such as the Iotek8000/7030 blend utilized in the cover compositions disclosed in U.S.Pat. No. 4,911,451. Moreover, included in new acrylic acid based highacid ionomer resins were numerous cation neutralized high acid ionomerresins previously not available, such as those acrylic acid based highacid ionomer resins neutralized to various degrees by the manganese,lithium, potassium, magnesium, calcium and nickel salts. Furthermore,the new cation neutralized acrylic acid based high acid ionomersproduced C.O.R. and hardness values greater than those shown by themethacrylic acid based high acid ionomer resins recently produced byDuPont (i.e. Surlyn® 8422 (Na) and Surlyn® 8162 (Zn)) and the acrylicacid based high acid resins experimentally produced by Exxon (i.e. IotekEX-959 and Ex-960 (Zn)), collectively referred to as “the controls.”

In addition, the results produced by Formulation Nos. 1 through 3directed to the sodium ion neutralized ethylene-acrylic acid copolymersand Formulation Nos. 15 through 17 directed to the zinc ion neutralizedethylene-acrylic acid copolymers in comparison to the new Iotek highacid ethylene acrylic acid ionomers were also of interest. As indicatedabove, Escor® or Iotek Ex-959 is a sodium ion neutralizedethylene-acrylic acid copolymer and Escor® or Iotek Ex-960 is a zincneutralized ethylene-acrylic acid copolymer. According to Exxon, Ioteks959 and 960 contain from about 19.0 to about 21.0% by weight acrylicacid with approximately 30 to about 70 percent of the acid groupsneutralized with sodium and zinc ions, respectfully.

Formulation No. 2 (i.e. 5.66 wt-% sodium salt, 54 wt-% neutralization,2.4 melt index, 0.808 C.O.R. and 73 Shore D hardness) is somewhatsimilar to Iotek 959 and Formulation No. 16 (i.e. 13.9 wt-% zinc salt,53 wt-% neutralization, 0.9 melt index, 0.797 C.O.R. and 69 Shore Dhardness) is somewhat similar to Iotek 960.

However, not only did the new cation neutralized acrylic acid based highacid ionomers of the present invention exhibit similar or betterresilience (C.O.R.) at comparable or better hardness values than thoseexhibited by the sodium or zinc high acid Iotek ionomers, as a result ofthe neutralization of the acrylic acid/ethylene copolymer with severaldifferent cation salts, to a number of different neutralizationpercentages, a wide variety of new cation neutralized acrylic acid basedhigh acid ionomers were produced having improved resilience and hardnessvalues. These new cation neutralized high acid ionomer resins areparticularly valuable in the field of golf ball production.

More particularly, the development of a number of separate differentcation neutralized high acid ionomers besides the sodium or zinc highacid ionomers available from DuPont or Exxon, such as the new manganese,lithium, potassium, magnesium, calcium and nickel acrylic acid basedhigh acid ionomer resins, allows for the production of a wide variety ofcation neutralized high acid ionomer blends. Furthermore, since the newsodium or zinc neutralized high acid ionomers produced improvedproperties over those produced by the existing available sodium or zinchigh acid ionomers, a number of new cover compositions can be producedhaving enhanced characteristics.

Along this line, several of the cation neutralized acrylic acid basedhigh acid ionomer resins produced above which exhibited enhanced C.O.R.and Shore D hardness values were blended together and evaluated for thepurpose of determining whether any synergistic effects were producedparticularly with respect to enhanced C.O.R. values.

Specifically, from each group of the different cation neutralized highacid ionomer resins set forth in Table 7, the best overall ionomer(based upon C.O.R., melt index and Shore D hardness) was utilized toproduce a number of blends (“diblends” and “triblends”) and processed toproduce the cover component of multi-layered golf balls. The “diblends”consisted of 50/50 mixtures and the “triblends” consisted of a33.33/33.33/33.33 mixtures.

With respect to the blends set forth in Tables 8 and 9, Na refers toFormulation No. 3, C.O.R. (molded/finished) of 0.812/817; Mn refers toFormulation No. 6, C.O.R. (molded/finished) of 0.814/0.814; Li refers toFormulation No. 10, C.O.R. (molded/finished) of 0.818/0.819; K refers toFormulation No. 13, C.O.R. (molded/finished) of 0.805/0.809; Zn refersto Formulation No. 16, C.O.R. (molded/finished) of 0.797/0.796; Mgrefers to Formulation No. 18, C.O.R. (molded/finished) of 0.814/0.820;Ca refers to Formulation No. 21, C.O.R. (molded/finished) of0.813/0.812; Ni refers to Formulation No. 28, C.O.R. (molded/finished)of 0.799/0.817; and 50/50 Iotek 8000/7030 refers to control of 50/50blend of Iotek 8000/7030, C.O.R. (molded/finished) of 0.810/0.812.

The C.O.R. values of the “diblends” and “triblends” were then evaluatedafter molding with a center stock having the following composition:

MATERIAL WEIGHT (phr) BR-1220¹ 70.70 Taktene 220² 29.30 React Rite ZDA³31.14 Zinc Oxide 6.23 Zinc Stearate 20.15 Lirnestone 17.58 Ground Flash(20-40 mesh) 20.15 Blue Masterbatch .012 Luperco 231XL⁴ .89 or Trigonox29/40⁵ Papi 94⁶ .50 ¹BR-1220 is high cis-polybutadiene from ShellChemical Co., Houston Texas. ²Taktene is high cis-polybutadiene fromPolysar ChemicaL. ³ZDA is zinc diacrylate. ⁴Luperco 231XL is aperoxide-free radical initiator manufactured and sold by Atochem,Buffalo, New York. ⁵Trigonox 29140 is peroxide-free radical initiatormanufactured and sold by Akzo Chemie America, Chicago, Illinois. ⁶Papi94 is a polymeric diisocyanate available from Dow Chemical Co., Midland,Michigan.

In addition, the molded balls were coated and finished according to theprocedure mentioned above. The C.O.R. values of the finished balls weredetermined in order to evaluate whether any improvement in resiliencewas produced. Generally, it is typical to observe a 0.002 to 0.003 pointpick up in C.O.R. values of the finished balls in comparison to themolded balls. The results are set forth in Tables 8A, 8B and 9 below.

TABLE 8A Diblends (50/50 Blends) C.O.R. (Molded/Finished) ValuesFormulation No. Blend C.O.R. (Molded/Finished) 31 Na/Mn .813/.818 32Na/Li .813/.818 33 Na/K .809/.816 34 Na/Zn .811/.818 35 Na/Mg .813/.81936 Na/Ca .811/.819 37 Mn/Li .811/.817 38 Mn/K .811/.818 39 Mn/Zn.807/.814 40 Mn/Mg .809/.816 41 Mn/Ca .809/.816 42 Li/K .810/.817 43Li/Zn .813/.819 44 Li/Mg .812/.820 45 Li/Ca .811/.818 46 K/Zn .810/.81547 K/Mg .811/.820 48 K/Ca .810/.817 49 Zn/Mg .807/.814 50 Zn/Ca.808/.814 51 Mg/Ca .801/.818 52 Na/Ni .809/.815 53 Mn/Ni .807/.814 54Li/Ni .809/.816 55 K/Ni .809/.816 56 Zn/Ni .799/.804 57 Mg/Ni .805/.81358 Ca/Ni .807/.815 59 Iotek 959/960 .811/.818 60 Control .809/NA 61Control .806/NA Controls are Formulation No. 59, a 50/50 blend of Iotek959/960; Formulation No. 60 a 75/25 blend of Surlyn 8162/8422; andFormulation No. 61 a 50/50 blend of Iotek 8000/7030.

TABLE 8B Synergy Values of the DiBlends (COR) exp- Final Final FinalFormulation No. Salt 1 Salt 2 (COR) calc (COR) exp (COR) calc (COR) calc(COR) exp (COR) Diff. 31 Na Mn 813.0 813.0 0.0 815.5 818.0 2.5 32 Na Li815.0 813.0 −2.0 818.0 818.0 0.0 33 Na K 808.0 809.0 1.0 813.0 816.0 3.034 Na Zn 804.5 811.0 6.5 806.5 818.0 11.5 35 Na Mg 813.0 813.0 0.0 818.5819.0 0.5 36 Na Ca 812.5 811.0 −1.5 814.5 819.0 4.5 37 Mn Li 816.0 811.0−5.0 816.5 817.0 0.5 38 Mn K 809.0 811.0 2.0 811.5 818.0 6.5 39 Mn Zn805.5 807.0 1.5 805.0 814.0 9.0 40 Mn Mg 814.0 809.0 −5.0 817.0 816.0−1.0 41 Mn Ca 813.5 809.0 −4.5 813.0 816.0 3.0 42 Li K 811.0 810.0 −1.0814.0 817.0 3.0 43 Li Zn 807.5 813.0 5.5 807.5 819.0 11.5 44 Li Mg 816.0812.0 −4.0 819.5 820.0 0.5 45 Li Ca 815.5 811.0 −4.5 815.5 818.0 2.5 46K Zn 800.5 810.0 9.5 802.5 815.0 12.5 47 K Mg 809.0 811.0 2.0 814.5820.0 5.5 48 K Ca 806.0 810.0 4.0 810.5 817.0 6.5 49 Zn Mg 805.5 807.01.5 808.0 814.0 6.0 50 Zn Ca 805.0 808.0 3.0 804.0 814.0 10.0 51 Mg Ca813.5 810.0 −3.5 816.0 818.0 2.0 52 Na Ni 805.5 809.0 3.5 817.0 815.0−2.0 53 Mn Ni 806.5 807.0 0.5 815.5 814.0 −1.5 54 Li Ni 808.5 809.0 0.5818.0 816.0 −2.0 55 K Ni 801.5 809.0 7.5 813.0 816.0 3.0 56 Zn Ni 798.0799.0 1.0 806.5 804.0 −2.5 57 Mg Ni 806.5 805.0 −1.5 818.5 813.0 −5.5 58Ca Ni 806.0 807.0 1.0 814.5 815.0 0.5

In Table 8B above, the C.O.R. synergy values are based upon the datafrom Table 7 of the various metal cation neutralized high acid acrylicacid based ionomer resins and the following calculations:

(COR) calc=coefficient calculated as weighted average of as-molded COR'sfor polymers of salts 1 and 2

(COR) exp=experimental as-molded COR for blend

FINAL (COR)calc=coefficient calculated as weighted average of finishedCOR's for polymers of salts 1 and 2

FINAL (COR) exp=experimental finished COR for blend

FINAL (COR) diff=difference between FINAL (COR) exp and FINAL (COR)(calc)

As noted in Table 8B, positive synergy in resilience is observed fornearly all of the finished (final) blends, with substantial synergybeing produced in Formulation Nos. 34, 38, 39, 43, 46, 48, 49, 50.

Moreover, the diblends were also evaluated against a control FormulationNo. 59 (see Table 8A), a 50/50 blend of Iotek 959/960, the bestavailable high acid blends, with respect to improved C.O.R. values (i.e.811/0.818). Similar or enhanced C.O.R. values (molded/finished) wereobserved in Formulation Nos. 31 (Na/Mn), 32 (Na/Li), 34 (Na/Zn), 35(Na/Mg), 36 (Na/Ca), 38 (Mn/K), 43 (Li/Zn), 44 (Li/Mg), 45 (Li/Ca), and47 (K/Mg).

Furthermore, when reviewed for cold cracking, with the exception ofFormulation No. 35, all of the diblends tested exhibited resistance tobreaking. With respect to Formulation No. 35, some breakage did occurwith 2 out of the 12 balls tested exhibiting breakage.

When the small test sample of the triblends were evaluated (see Table 9below) in comparison to a 50/50 blends of the low acid acrylic acidbased hard ionomers (i.e. Iotek 8000/7030 U.S. Pat. No. 4,911,451), allof the cation neutralized high acid acrylic acid based triblendsproduced enhanced C.O.R. values upon molding and finishing. In addition,when subjected to cold cracking, no breakages were observed.

TABLE 9 C.O.R. C.O.R. Formulation Cation Blend Molded Finished Ball 62Zn/Li/K .819 .828 63 Na/Zn/Li .821 .829 64 Iotek 8000/7030 .816 .819 65Na/Mn/Ca .820 .828 66 Na/K/Nn .821 .829 67 Na/K/Mg .821 .829

Consequently, not only are a number of new cation neutralized acrylicacid based high acid ionomers now available for golf ball coverconstruction, these new cation neutralized acrylic acid based high acidionomers may be blended together in various combinations to producecover compositions exhibiting enhanced resilience (i.e. distance) due tothe synergies noted above.

Example 2

In order to determine whether the diblends or triblends of the newcation neutralized acrylic acid based high acid ionomer resins produceddifferent results when dry blended (i.e. prepared as simple dry blendsof pre-made single cation neutralized acrylic acid based high acidionomers, such as those set forth in Example 1 above) or when producedas “in-situ” cation blends (i.e. the cations were first blended and thenadded to the acrylic acid/ethylene copolymers in the Banbury mixer), anumber of comparison reactions were generated. Specifically, in-situFormulation Nos. 68-72 in Table 10 below correspond to dry-blendedFormulation Nos. 31, 32, 43, 44 and 46, respectively, and in-situFormulation Nos. 73 and 74 in Table 10 below correspond to dry-blendedFormulation Nos. 62 and 63, respectively.

TABLE 10 C.O.R C.O.R. Spin Rate Shore D Formulation No. Cation BlendMolded Finished 9-Iron, RPM Hardness 68 Na/Mn .822 .828 5,008 74 69Na/Li .820 .828 5,820 70 70 Li/Zn .820 .825 5,425 71 71 Li/Mg .821 .8285,451 73 72 Zn/K .817 .821 5,934 69 73 Li/Zn/K .822 .826 5,266 71 74Na/Li/Zn .821 .824 5,165 71 75 Iotek .819 .824 5,926 959(Na)/960(Zn)Tour Edition® 100 10,124  Tour Edition® 90 9,821 Top-Flite® XL II 6,942

The results indicated that little difference in C.O.R. was produced(relative to a control of 50/50 mixture of the high acid Iotek 959/960)whether a dry blending process or an in-situ blending process was used.Moreover, the data further clearly indicated that the cation neutralizedacrylic acid based high acid ionomer blends of the present inventiongenerally exhibit higher C.O.R. values and significantly lower spinrates than the best acrylic acid based high acid ionomers (i.e. theIoteks 959 (Na)/960 (Zn) blend), see Formulation Nos. 68, 70, 71, 73 and74 in comparison to Formulation No. 75 (control). The lower C.O.R. valueand the substantially similar spin rate produced by the Zn/K blend inFormulation 72 was attributed to the slightly lower hardness of thisblend versus the others. As indicated in Table 7, the K and Zn acrylicacid based high acid ionomers are a little softer than the Na, Mn, Liand Mg acrylic acid based high acid ionomers. Similarly, the higher spinrate of the Na/Li blend in Formulation 69 was due to its relativesoftness versus the other blends. In addition, other more subtle factorsmay also be at play, such as differences in coefficient of friction,deformation under load, etc., which have not quantified.

In addition, when compared with a number of commercially available ballsproduced by Spalding & Evenflo Companies, Inc., the assignee of thepresent invention, with low acid ionomer resin covers (i.e. the TourEdition® 100, Tour Edition® 90 and Top-Flite® XL II balls), the spinrates of the cation neutralized acrylic acid high acid ionomer blends ofthe present invention (i.e. Formulations 68-75) exhibited much lowerspin rates. Consequently, the cation neutralized acrylic acid based highacid ionomer blends of the present invention produced, when utilized toformulate the cover of a multi-layered golf ball, a much harder surfacethen those produced by the low acid ionomer covers presently available.This may be desirable to a golfer who imparts unmanageable spin(slice/hook) to the ball and thereofre may benefit from a “low spin”ball.

Example 3

Acrylic Acid Based High Acid Ionomer Di-Blends Containing Varying Ratiosof Cation Neutralized Acrylic Acid Based High Acid Ionomers

In addition to the 50/50 blends of various combinations of the newcation neutralized acrylic acid based high acid ionomers set forth inExample 1, di-blends varying from 25/75 to 75/25 ratios were producedutilizing the more preferred diblends in the “in-situ” process describedin Example 2. In this regard, the more preferred diblend formulationsset forth in Example 1 (i.e. Formulation No. 31 (Na/Mn), Formulation No.32 (Na/Li), Formulation 43 (Li/Zn), Formulation No. 44 (Li/Mg), andFormulation No. 46 (Zn/K)) were produced in-situ in 50/50, 25/75 and75/25 combinations according to the following formulations:

TABLE 11 Formulations Ingredients 76 77 78 79 80 81 82 83 84 85 Acid 100100 100 100 100 100 100 100 100 100 Copolymer (Primacor 5981) NaOH 2.01.0 3.0 2.0 1.0 3.0 — — — — Mn Acetate 15.0 22.5 7.5 — — — — — — —Lithium — — — 3.1 4.7 1.6 3.1 1.6 4.7 3.1 Hydroxide Monohydrate Zinc — —— — — — 8.00 12.0 4.0 — Acetate Potassium — — — — — — — — — — HydroxideMagnesium — — — — — — — — — 10.5 Acetate Formulation No. Ingredients 8687 88 89 90 Primacor 5981 100 100 100 100 100 Lithium Hydroxide 1.6 4.7— — — Magnesium Acetate 15.8 5.3 — — — Zinc Acetate — — 8.00 12.0 4.0Potassium Hydroxide — — 4.50 2.25 6.75

The di-blends produced the following C.O.R. values:

TABLE 12 Formulation No. Cation Blend C.O.R. (Molded) 76 50/50 Na/Mn.820 77 25/75 Na/Mn .821 78 75/25 Na/Mn .825 79 50/50 Na/Li .822 8025/75 Na/Li .822 81 75/25 Na/Li .823 82 50/50 Li/Zn .816 83 25/75 Li/Zn.804 84 75/25 Li/Zn .825 85 50/50 Li/Mg .823 86 25/75 Li/Mg .822 8775/25 Li/Mg .821 88 50/50 Zn/K .820 89 75/25 Zn/K .798 90 25/75 Zn/K.821 Control is a 50/50 Iotek Low Acid Ionomer Blend (8000/7030), C.O.R.(molded) .817

The results indicated that in general the new cation neutralized acrylicacid based high acid ionomer diblends produced enhanced C.O.R. valuesover the known acrylic acid based low acid ionomer blends. SeeFormulation Nos. 76-81, 84-88 and 90. While Formulation 82 produced alower C.O.R. value than expected, the data suggested that in some cases,a 50/50 blend is not optimal (particularly in the Zn/K and the Li/Znblends), while in others (i.e. Li/Mg, Na/Li) the blend ratio is notsignificantly different.

Example 4

Since the data set forth in Examples 1-3 indicated the resilience(C.O.R.) and/or hardness properties of the cover compositions can besubstantially enhanced through the use of the new cation neutralizedacrylic acid based high acid ionomers and/or diblends or triblends ofsuch ionomers, the molecular weight property of the acrylicacid/ethylene copolymers utilized to produce the ionomers was evaluated.Specifically, the molecular weight of the acid copolymers was assessedfor the purpose of determining whether further enhanced properties canbe produced by varying the molecular weight of the acid copolymer.

In this regard, since the data indicated that there was littledifference between using the dry blending process or the in-situblending method for processing the cations, the in-situ method ofproducing the cation neutralized high acid ionomer blends was used inthis analysis.

Along this line, the diblend and triblends set forth in Formulation Nos.68, 73 and 74 are essentially the same as those set forth below inFormulation Nos. 91, 94 and 97, respectively. However, since a differentbatch of cores was utilized than those used in Example 2, the C.O.R. 'sare slightly lower. While the cores utilized in the present Example wereof the same composition, the lower C.O.R. was due to the age of thecores, i.e. molded cores will lose C.O.R. upon aging mainly due tomoisture pickup. Formulation Nos. 92-93, 95-96 and 98-99, are similar tothose set forth in Formulation Nos. 91, 94 and 97, respectively, withthe exception that the molecular weight of the acrylic acid/ethylenecopolymer utilized was varied. Specifically, Primacor 5983 and Primacor5990 both contain the same acid content as Primacor 5981 (i.e. 20 weightpercent acrylic acid) but have lower viscosities (lower molecularweights) and lower densities. Primacor 5981 has a melt index of 300 g/10minute (ASTM Method D-1238 at 190° C.) and a Brookfield viscosity of51,000 cps at 350° F. Primacor 5983 has a melt index of 500 and aBrookfield viscosity of 26,000 cps at 350° F.; and Primacor 5990 has amelt index of 1300 and viscosity of 13,000 cps at 350° F.

The resilience (C.O.R.) of the molded balls produced utilizing thedifferent molecular weight acrylic acid/ethylene copolymers are setforth below in Table 13.

TABLE 13 C.O.R. Formulation No. Cations Acid Copolymer (MOLDED) 91 Na/MnPrimacor 5981 .813 92 Na/Mn Primacor 5983 .805 93 Na/Mn Primacor 5990All Balls crack 94 Li/Zn/K Primacor 5981 .814 95 Li/Zn/K Primacor 5983.809 96 Li/Zn/K Primacor 5990 All Balls crack 97 Na/Li/Zn Primacor 5981.813 98 Na/Li/Zn Primacor 5983 .808 99 Na/Li/Zn Primacor 5990 All Ballscrack

The data indicated that a higher molecular weight acid copolymer ispreferred for obtaining high resilience (i.e. C.O.R.) and requiredtoughness.

The invention has been described with reference to the preferredembodiment. Obviously, modifications and alterations will occur toothers upon a reading and understanding of the preceding detaileddescription. It is intended that the invention be construed as includingall such alterations and modifications insofar as they come within thescope of the appended claims or the equivalents thereof.

Having thus described the preferred embodiments, the invention is nowclaimed to be:
 1. A metal cation neutralized high acid ionomer resincomprising a copolymer of greater than 16% by weight of an alpha,beta-unsaturated carboxylic acid and the balance an alpha-olefin, ofwhich about 10 to about 90% of the carboxyl groups of the copolymer areneutralized with a metal cation selected from the group consisting ofmanganese, lithium, potassium, calcium and nickel ions.
 2. The metalcation neutralized high acid ionomer resin of claim 1, wherein saidalpha, beta-unsaturated carboxylic acid is acrylic acid.
 3. The metalcation neutralized high acid ionomer resin of claim 1, wherein saidalpha-olefin is ethylene.
 4. The metal cation neutralized high acidionomer resin of claim 1, wherein said copolymer comprises from about17% to about 25% by weight of an alpha, beta-unsaturated carboxylicacid.
 5. The metal cation neutralized high acid ionomer of claim 1,wherein said copolymer comprises from about 18.5% to about 21.5% byweight of an alpha, beta-unsaturated carboxylic acid.
 6. A metal cationneutralized high acid ionomer resin comprising a copolymer of about 20%by weight of an alpha, beta-unsaturated carboxylic acid and the balancean olefin, of which about 10 to about 90% of the carboxyl groups of thecopolymer are neutralized with a metal cation selected from the groupconsisting of manganese, lithium, potassium, calcium and nickel ions. 7.The metal cation neutralized high acid ionomer resin of claim 6, whereinsaid alpha, beta-naturalized carboxylic acid is acrylic acid.
 8. Themetal cation neutralized high acid ionomer resin of claim 6, whereinsaid alpha-olefin is ethylene.
 9. A metal cation neutralized high acidionomer resin comprising a copolymer of about 20% by weight acrylic acidand the remainder ethylene, of which 10 to 90% of the carboxyl groups ofthe copolymer are neutralized with a metal cation selected from thegroup consisting of manganese, lithium, potassium, magnesium, calciumand nickel ions.
 10. A metal cation neutralized high acid ionomer resincomprising a copolymer of about 20% by weight acrylic acid and theremainder ethylene, of which 10 to 90% of the carboxyl groups of thecopolymer are neutralized with a metal cation selected from the groupconsisting of sodium, manganese, lithium, potassium, zinc, magnesium,calcium and nickel ions.
 11. A method for producing a metal cationneutralized high acid ionomer resin comprising the steps of: a)providing a copolymer comprised of greater than 16% by weight of analpha, beta-unsaturated carboxylic acid and an olefin; and b)neutralizing from about 10% to about 90% of the carboxylic acid groupsof the copolymer with a metal cation selected from the group consistingof manganese, lithium, potassium, calcium and nickel ions.
 12. Themethod of claim 11, wherein said copolymer comprises from about 17% toabout 25% by weight of an alpha, beta-unsaturated carboxylic acid. 13.The method of claim 11, wherein said copolymer comprises from about18.5% to about 21.5% by weight of an alpha, beta-unsaturated carboxylicacid.
 14. The method of claim 11, wherein the alpha, beta-unsaturatedcarboxylic acid is acrylic acid.
 15. The method of claim 11, wherein theolef in is ethylene.
 16. The method of claim 11, wherein theneutralization is carried out at a temperature of from about 250° toabout 500° F.
 17. The method of claim 11, wherein the metal cationsource is an acetate, oxide or hydroxide salt of manganese, lithium,potassium, calcium, magnesium or nickel.
 18. The manganese neutralizedhigh acid ionomer resin produced by the method of claim
 11. 19. Thelithium neutralized high acid ionomer resin produced by the method ofclaim
 11. 20. The potassium neutralized high acid ionomer resin producedby the method of claim
 11. 21. The metal cation neutralized high acidionomer resin of claim 1 wherein the ionomer resin is water insoluble.22. The metal cation neutralized high acid ionomer resin of claim 6wherein the ionomer resin is water insoluble.
 23. The metal cationneutralized high acid ionomer resin of claim 9 wherein the ionomer resinis water insoluble.
 24. The metal cation neutralized high acid ionomerresin of claim 10 wherein the ionomer resin is water insoluble.
 25. Themetal cation neutralized high acid ionomer resin of claim 11 wherein theionomer resin is water insoluble.